For relatively small exhaust turbochargers to be used in an internal combustion engine for vehicles, etc., exhaust gas from the engine, adopted is the configuration in which exhaust gas from the engine fills a scroll formed in a turbine housing, and passes through a plurality of nozzle vanes provided on an inner circumferential side of the scroll to act on a turbine rotor provided on an inner circumferential side of the plurality of nozzle vanes.
Further, a variable displacement turbocharger equipped with a variable nozzle mechanism which is configured to vary an angle of a plurality of nozzle vanes is often used.
This variable nozzle mechanism is configured to vary the angle of the nozzle vane, and a full close position (the minimum use opening position) or a full open position (the maximum use opening position) of the nozzle vane is set from the perspective of safety and required performance of a turbocharger. The full open position or full close position is normally regulated by a stopper mechanism.
One example of the stopper mechanism is described in Patent Document 1 (JP 2000-199433 A). According Patent Document 1, a roller pin member serving as a stopper pin is configured to control the full open angle of the nozzle vane by bringing a large-diameter disk part of the roller pin member into contact with a side face of one of adjacent two opening-closing levers which are disposed on both sides of the roller pin member and control the full close angle of the nozzle vane by bringing the large-diameter disk part of the roller pin member into contact with a side face of the other of the adjacent two opening-closing levers.
Further, described in Patent Document 2 (JP 2002-256877 A) is to control a vane angle without providing a stopper pin. As illustrated in FIG. 9 of the attached drawings, a variable nozzle mechanism for a variable capacity turbine is configured such that two full-opening stopper surfaces 03 are provided on at least two neighboring lever plates 01 to move nozzle vanes toward the opening direction and stop the nozzle vanes at the full-opening position by contacting the two neighboring lever plates to each other and a closing stopper surface 07 is provided on each of the lever plate 01 and the nozzle mount 05 to stop the nozzle vanes at the minimum opening angle position by contacting the closing stopper surfaces 07 to each other at the minimum opening angle position of the nozzle vanes.